Consistent with the goal of RFA-MD-12-003, this application proposes to address health disparities among the identified minority groups: Asian Americans (AAs), Pacific Islanders (PIs), and multiple-race individuals (MRs). AAs, PIs, and MRs are among the most understudied and the least known minority populations, especially for substance problems and treatment needs. The lack of population-based data on the incidence and prevalence of use of alcohol and 9 drug classes as well as the patterns and magnitude of substance-related disorders and treatment needs for each group make it almost impossible to develop evidence-based programs and policies to address substance-related burdens for these fastest-growing and underserved populations. Capitalizing on the largest national studies of substance use and disorders (National Survey on Drug Use and Health, NSDUH) and the largest psychiatric electronic medical record data repository (MindLinc) in the US, the proposed team will examine substance abuse and treatment gaps for each group. Study aims include to (a) examine the incidence and determinants of first use (onset) of alcohol and nine major drug classes, including incidence trends, risk periods for initiation, and correlates of recent initiatin; (b) determine the patterns, sequences, and correlates of polysubstance use and substance disorders; (c) investigate the prevalence, patterns, and correlates of substance abuse treatment use, including the location of services received, the primary abused substance for receiving treatment, and perceived unmet needs for and barriers to treatment use; (d) elucidate comprehensive patterns of comorbid disorders and their temporal associations; and (e) determine pathways to psychiatric treatment, including treatment entry settings, primary disorders for treatment entry (substance vs. non-substance disorders), modes of treatment, and treatment responses. Analyses for each aim will examine differences across racial groups to gauge the extent of health disparities (AAs, PIs, MRs vs. whites) and within each group to provide an in-depth knowledge base for each specific population. The findings will identify the heightened risk periods for initiating alcohol or drug use and at-risk subgroups to facilitate targeting primary prevention programs. They also will specify subgroups showing elevated odds of polysubstance use, drug disorders, and other mental disorders, so they can be targeted for focused interventions to reduce serious consequences. The field will understand better the unmet needs for and barriers to treatment use among AAs, PIs, and MRs. Given the Patient Protection and Affordable Care Act, such a comprehensive knowledge base is timely needed to guide evidence-based research, intervention, policymaking to reduce burdens and costs associated with substance use. The largest national data files for these groups will be complemented by longitudinally collected treatment data to provide a fuller picture of substance abuse treatment needs for these understudied groups. This project constitutes an initial and cost-effective step to study the distributions, correlates, courses, consequences, and treatment gaps of substance problems among AAs, PIs, and MRs.